1. Field of the Invention
The present invention generally relates to the field of fiber-optic systems, and in particular to methods and apparatuses for optical isolation in high peak power fiber-optic systems.
2. Description of the Related Art
In high power fiber-optic systems, optical isolators are used to protect low-power components from damage that may be caused by back-reflected light from amplifiers or other components. For example, a fiber-optic optical isolator may be used to protect a laser light source or a pre-amplifier from destabilizing or damaging feedback.
Generally, a fiber-optic optical isolator is a non-reciprocal optical device based on magneto-optic rotation of a plane of polarization of a propagating optical signal. Such a phenomenon is observed in certain crystals and commonly referred to as the “Faraday effect.” In the high power systems, the back-reflected light may carry enough power to cause irreversible physical damage to an output fiber of the optical isolator. Such damage often occurs at an end facet the output fiber inside of the optical isolator because there is typically a significant change in index of refraction between the output fiber and atmospheric gas, or other medium, disposed on the other side of the end facet.